Alpha-numeric indicator

ABSTRACT

An alpha-numeric indicator including a plurality of phosphor coated anode elements on opposite sides of a transparent substrate, the characters being formed utilizing anode elements from one or both sides of the substrate. Electrons for exciting the phosphors are provided by a thin wire filament structure located on both sides of the substrate.

United States Patent [151 3,657,587 Kegelman [451 Apr. 18, 1972 54] ALPHA-NUMERIC INDICATOR 2,922,993 1/1960 Sack ..340/324 7 3,376,454 4/1968 Stone ..3l3/ 109.5 [72] Inventor. Thomas D. Kegelman, Rtdgefield, Conn. 3,509,402 4,1970 DuBois 313/1095 [73] Assignee: Computer-Optics, lnc., Newtown, Conn. lz l fimj "3 /10 5 [22] Filed: Nov. 3,1969 ash ..3l5/3l6 21 A N 873 377 Primary Examiner-Herman Karl Saalbach 1 pp 0 Assistant Examiner-C. Barafl' Attorney-Morgan, Finnegan, Durham & Pine [52] U.S.Cl ..313/109.5,3l3/lO8,3l3/l i2 [51] Int. Cl. ..H0 lj 17/48 [57] ABSTRACT [58] Field of Search ..3l3/l09.5, 108; 340/324;

250/217; 315/316 An alpha-numerlc indicator including at plurality of phosphor coated anode elements on opposite sides of a transparent substrate, the characters being formed utilizing anode elements [56] References Cited from one or both sides of the substrate. Electrons for exciting UNfl-ED STATES PATENTS the phosphors are provided by a thin wire filament structure located on both sides of the substrate, 3,435,270 3/1969 Vodicka ..,...3l3/l08 3,384,770 5/1969 Vodicka ..3l3/l08 5 Claims, 5 Drawlng Figures z r q i l l 4' /a i 9 2 I l F I l9 i l 4 fl I 2 l .37 35 i l 33 J5 34 12 I l l l \g l I I yw V I r to BACKGROUND OF THE INVENTION A This invention relates to alpha-numeric indicating devices and, while not limited thereto, relates particularly to the class of devices wherein a character or symbol is formed by exciting phosphors through the selective energization of one or more anode elements.

Alphanumeric indicators are familiar read-out devices and find utility in displaying output information, such as in a digital voltmeter. The ideal indicator would display selected characters of symbols at the same place with the definition of a printed letter. In the past, compromises have been made either with respect to character definition or the superpositioning of the characters.

One approach, commonly known as the Nixie tube, involves the use of individually complete preformed characters which are displayed by selective energization. This approach is illustrated in US. Pat. No. 2,906,906. Here the character definition is excellent, but the price paid is that the elements are stacked and there is an in-and-out effect as the various characters are energized. From the standpoint of the viewer this lack of true superpositioning is undesirable.

A second approach, is to take a planar array of segments of characters and form the desired character by energizing selected segments in combination. Here, character definition is sacrificed at the expense of eliminating the "in-and-out" effect, since the number of available segments is limited. This second approach is illustrated by U.S. Pat. No. 2,957,098.

BRIEF SUMMARY OF THE INVENTION The indicating device according to the invention overcomes the deficiencies of the prior devices by utilizing a plurality of transparent phosphor coated anode elements on both sides of a transparent substrate. Characters are formed by selectively energizing anode elements from one or both sides of the substrate thereby substantially increasing the number of available character forming elements. Electrons for exciting the phosphors are provided by cathodes located on opposite sides of the substrate preferably in the form of a dispersed, thin wire structure so that the excited phosphor regions are visible through the cathode structure.

BRIEF DESCRIPTION OF THE DRAWINGS DETAILED DESCRIPTION The construction and operation of the invention will be described with respect to FIGS. 1 through 5. For purposes of this description the assumption will be made that the anode segments shown in FIG. 2 are exposed to the observer and that those shown in FIG. 1 are on the side away from the viewer.

FIG. 1 depicts a particular configuration of character elements 1 comprised of the odd numbered segments 3 through 25 FIG. 2 depicts the complementary configuration of character elements 2 composed of the even numbered segments 4 through 28.

To form the numerals zero through nine the following combinations of elements are employed:

Numeral Character Segments 7, 9. l0. 2, I4, 23, 26 and 28 17 and 28 l0. I2, I14. l6. I8, 20, 6, 3 and 28 l0, l2, I4. I6, 18, 20. 24, 26 28 and 4 13, 7,15." and I8 12,11, 9. 7, 13.18.24, 26 28 and 4 14, l2, l0, 9, 7, 5, 4. 28, 26, 24, 18

and 20 I2, 21, 19 and 22 8 4, 6, 20, l8. l6, l4, 12, 10, 8 24, 26

. and 28 9 16, I4, 112, 10,8, 20, 18. 23, 26, 28

and 4- OM-huN-O The character elements illustrated in FIGS. 1 and 2 are formed by silk screening conductive material onto the selected regions as indicated and by then coating the conductors with a luminescent material such as a phosphor in the regions where illumination is desired. Because the elements in FIGS. 1 and 2 will, in essence, be superimposed on one another it is necessary to use a transparent substrate and transparent conductors. A suitable conductor material is a tin oxide composition designated NESA. The particular phosphor selected will depend on the speed with which the selected character must appear and the desired retention time of the display after the energizing potential is removed from the anode. Of the green phosphors, an example of a low speed phosphor would type P-20, an example of a medium speed phosphor would be type P1 and an example of a high speed phosphor would be type P-3 l.

The use of two sets of character elements greatly enhances the character definition obtainable as compared to a single planar array of elements. This is true not only because a greater number of elements may be employed, but because overlap of elements in FIG. 1 with those of FIG. 2 is not objec tionable. This permits the use-of shapes of elements not possible with a single planar array.

There is also a slight fringing effect associated with an energized element so that the gaps between elements necessary for electrical isolation disappear when adjacent elements are energized.

FIG. 3 illustrates one method of energizing the character elements shown in FIGS. 1 and 2. A source of positive potential 29 is connected to selected elements by the switching arrangement 27. When an element is connected to the source of positive potential 29, in the presence of a source of electrons, the luminescent coating on the transparent conductor will glow. Mechanical switches are shown but, of course, electronic switching could be employed.

FIG. 4 illustrates the invention utilized as a read-out device for digital information. A digital code, for example, designating numeral 7 is fed to selection circuit 30 which decodes this information and selects the proper elements to form the designated numeral. Selection circuit 30 may be a resistor or diode matrix or other type of logic network. Utilizing the character elements in FIGS. 1 and 2, the number seven would appear as shown in FIG. 4.

FIG. 5 illustrates the invention embodied in an indicator tube. Conductors 33 connect the anode elements to pins 36 in the base of envelope 31. Substrate 22 may be composed of any material transparent to the luminescence produced by the energized segments. Glass of thickness 0.003 inches has been found satisfactory. While substrate 32 is here shown as planar, a curved substrate could be employed as long as significant distortion is not introduced.

Two sources of electrons are shown in FIG. 5 in heated cathodes 34 and 35. Tungsten wire with an oxide coating and a 3 to 4 mil diameter is suitable for the cathode construction. The cathode 35 is interposed between the viewer 37 and the substrate 32 but the cathode wire is small enough in diameter so as not to interfere with the viewers vision of the illuminated phosphor regions.

It is to be understood that although only one embodiment of the invention is described in detail, there are other configurations of character elements and other materials which can be employed in accordance with the teachings of the invention. The invention is more particularly defined in the appended claims.

I claim: 1. A character display device including a transparent substrate;

a plurality of transparent anode elements on each side of said substrate;

a phosphor coating covering at least a portion of each of said anode elements to provide a pattern of character elements, the character elements on one side of said substrate complementing the character elements on the other side;

circuit means coupled to said anode elements to supply an energizing potential to selected ones of said anode elements to obtain the desired character consisting of said character elements; and

a thin wire cathode structure located on opposite sides of said substrate to provide electrons for exciting the phosphor coatings covering anode elements energized by said circuit means.

2. An indicating device according to claim 1 wherein said character elements are readily visible through said thin wire cathode structure.

3. An indicating device according to claim 1 further including an evacuated glass envelope enclosing said substrate and said cathode structure.

4. A character display device including:

a transparent substrate;

a plurality of transparent anode elements on each side of said substrate;

a phosphor coating covering at least a portion of each of said anode elements to provide a pattern of character elements, the character elements on one side of said substrate complementing the character elements on the other side;

circuit means coupled to said anode elements to supply an energizing potential to selected ones of said anode elements to obtain the desired character consisting of said character elements; and

a source of electrons for exciting those phosphor coatings covering electrically energized anode elements, said source of electrons including a heated cathode consisting of a thin wire structure located on opposite sides of said substrate, said anode elements being visible through said thin wire structure.

5. A character display device according to claim 4 wherein said desired character comprises complementary character elements selected from both sides of said substrate. 

1. A character display device including a transparent substrate; a plurality of transparent anode elements on each side of said substrate; a phosphor coating covering at least a portion of each of said anode elements to provide a pattern of character elements, the character elements on one side of said substrate complementing the character elements on the other side; circuit means coupled to said anode elements to supply an energizing potential to selected ones of said anode elements to obtain the desired character consisting of said character elements; and a thin wire cathode structure located on opposite sides of said substrate to provide electrons for exciting the phosphor coatings covering anode elements energized by said circuit means.
 2. An indicating device according to claim 1 wherein said character elements are readily visible through said thin wire cathode structure.
 3. An indicating device according to claim 1 further including an evacuated glass envelope enclosing said substrate and said cathode structure.
 4. A character display device including: a transparent substrate; a plurality of transparent anode elements on each side of said substrate; a phosphor coating covering at least a portion of each of said anode elements to provide a pattern of character elements, the character elements on one side of said substrate complementing the character elements on the other side; circuit means coupled to said anode elements to supply an energizing potential to selected ones of said anode elements to obtain the desired character consisting of said character elements; and a source of electrons for exciting those phosphor coatings covering electrically energized anode elements, said source of electrons including a heated cathode consisting of a thin wire structure located on opposite sides of said substrate, said anode elements being visible through said thin wire structure.
 5. A character display device according to claim 4 wherein said desired character comprises complementary character elements selected from both sides of said substrate. 